Thank you for your concern everyone. She seems to be doing better, at least she doesn't seem to be in pain anymore, but she's still on pain meds. Spoke to my vet today and we agreed to give her the meds for at least a week. If the problems return once she's off medication, I have to continue the treatment. My vet suspects it's arthritis.

It's cooling down here right now, and this morning was the first time since last weekend that she ate all of her breakfast. She went back to her hiding place after breakfast, though, but I'm beginning to wonder if she has just started to like this place. She has a blanket there, and it's a quiet place... Apart from spending her days there, she's acting absolutely normal, so I really think she's doing better. They predicted very cold temperatures for the next days, so we'll see what happens...

Karen, that sounds like a great advice for the next heatwave... thanks a lot!